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Java example source code file (space.cpp)
The space.cpp Java example source code/* * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "classfile/systemDictionary.hpp" #include "classfile/vmSymbols.hpp" #include "gc_implementation/shared/liveRange.hpp" #include "gc_implementation/shared/markSweep.hpp" #include "gc_implementation/shared/spaceDecorator.hpp" #include "memory/blockOffsetTable.inline.hpp" #include "memory/defNewGeneration.hpp" #include "memory/genCollectedHeap.hpp" #include "memory/space.hpp" #include "memory/space.inline.hpp" #include "memory/universe.inline.hpp" #include "oops/oop.inline.hpp" #include "oops/oop.inline2.hpp" #include "runtime/java.hpp" #include "runtime/safepoint.hpp" #include "utilities/copy.hpp" #include "utilities/globalDefinitions.hpp" #include "utilities/macros.hpp" void SpaceMemRegionOopsIterClosure::do_oop(oop* p) { SpaceMemRegionOopsIterClosure::do_oop_work(p); } void SpaceMemRegionOopsIterClosure::do_oop(narrowOop* p) { SpaceMemRegionOopsIterClosure::do_oop_work(p); } HeapWord* DirtyCardToOopClosure::get_actual_top(HeapWord* top, HeapWord* top_obj) { if (top_obj != NULL) { if (_sp->block_is_obj(top_obj)) { if (_precision == CardTableModRefBS::ObjHeadPreciseArray) { if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) { // An arrayOop is starting on the dirty card - since we do exact // store checks for objArrays we are done. } else { // Otherwise, it is possible that the object starting on the dirty // card spans the entire card, and that the store happened on a // later card. Figure out where the object ends. // Use the block_size() method of the space over which // the iteration is being done. That space (e.g. CMS) may have // specific requirements on object sizes which will // be reflected in the block_size() method. top = top_obj + oop(top_obj)->size(); } } } else { top = top_obj; } } else { assert(top == _sp->end(), "only case where top_obj == NULL"); } return top; } void DirtyCardToOopClosure::walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top) { // 1. Blocks may or may not be objects. // 2. Even when a block_is_obj(), it may not entirely // occupy the block if the block quantum is larger than // the object size. // We can and should try to optimize by calling the non-MemRegion // version of oop_iterate() for all but the extremal objects // (for which we need to call the MemRegion version of // oop_iterate()) To be done post-beta XXX for (; bottom < top; bottom += _sp->block_size(bottom)) { // As in the case of contiguous space above, we'd like to // just use the value returned by oop_iterate to increment the // current pointer; unfortunately, that won't work in CMS because // we'd need an interface change (it seems) to have the space // "adjust the object size" (for instance pad it up to its // block alignment or minimum block size restrictions. XXX if (_sp->block_is_obj(bottom) && !_sp->obj_allocated_since_save_marks(oop(bottom))) { oop(bottom)->oop_iterate(_cl, mr); } } } // We get called with "mr" representing the dirty region // that we want to process. Because of imprecise marking, // we may need to extend the incoming "mr" to the right, // and scan more. However, because we may already have // scanned some of that extended region, we may need to // trim its right-end back some so we do not scan what // we (or another worker thread) may already have scanned // or planning to scan. void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) { // Some collectors need to do special things whenever their dirty // cards are processed. For instance, CMS must remember mutator updates // (i.e. dirty cards) so as to re-scan mutated objects. // Such work can be piggy-backed here on dirty card scanning, so as to make // it slightly more efficient than doing a complete non-detructive pre-scan // of the card table. MemRegionClosure* pCl = _sp->preconsumptionDirtyCardClosure(); if (pCl != NULL) { pCl->do_MemRegion(mr); } HeapWord* bottom = mr.start(); HeapWord* last = mr.last(); HeapWord* top = mr.end(); HeapWord* bottom_obj; HeapWord* top_obj; assert(_precision == CardTableModRefBS::ObjHeadPreciseArray || _precision == CardTableModRefBS::Precise, "Only ones we deal with for now."); assert(_precision != CardTableModRefBS::ObjHeadPreciseArray || _cl->idempotent() || _last_bottom == NULL || top <= _last_bottom, "Not decreasing"); NOT_PRODUCT(_last_bottom = mr.start()); bottom_obj = _sp->block_start(bottom); top_obj = _sp->block_start(last); assert(bottom_obj <= bottom, "just checking"); assert(top_obj <= top, "just checking"); // Given what we think is the top of the memory region and // the start of the object at the top, get the actual // value of the top. top = get_actual_top(top, top_obj); // If the previous call did some part of this region, don't redo. if (_precision == CardTableModRefBS::ObjHeadPreciseArray && _min_done != NULL && _min_done < top) { top = _min_done; } // Top may have been reset, and in fact may be below bottom, // e.g. the dirty card region is entirely in a now free object // -- something that could happen with a concurrent sweeper. bottom = MIN2(bottom, top); MemRegion extended_mr = MemRegion(bottom, top); assert(bottom <= top && (_precision != CardTableModRefBS::ObjHeadPreciseArray || _min_done == NULL || top <= _min_done), "overlap!"); // Walk the region if it is not empty; otherwise there is nothing to do. if (!extended_mr.is_empty()) { walk_mem_region(extended_mr, bottom_obj, top); } // An idempotent closure might be applied in any order, so we don't // record a _min_done for it. if (!_cl->idempotent()) { _min_done = bottom; } else { assert(_min_done == _last_explicit_min_done, "Don't update _min_done for idempotent cl"); } } DirtyCardToOopClosure* Space::new_dcto_cl(ExtendedOopClosure* cl, CardTableModRefBS::PrecisionStyle precision, HeapWord* boundary) { return new DirtyCardToOopClosure(this, cl, precision, boundary); } HeapWord* ContiguousSpaceDCTOC::get_actual_top(HeapWord* top, HeapWord* top_obj) { if (top_obj != NULL && top_obj < (_sp->toContiguousSpace())->top()) { if (_precision == CardTableModRefBS::ObjHeadPreciseArray) { if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) { // An arrayOop is starting on the dirty card - since we do exact // store checks for objArrays we are done. } else { // Otherwise, it is possible that the object starting on the dirty // card spans the entire card, and that the store happened on a // later card. Figure out where the object ends. assert(_sp->block_size(top_obj) == (size_t) oop(top_obj)->size(), "Block size and object size mismatch"); top = top_obj + oop(top_obj)->size(); } } } else { top = (_sp->toContiguousSpace())->top(); } return top; } void Filtering_DCTOC::walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top) { // Note that this assumption won't hold if we have a concurrent // collector in this space, which may have freed up objects after // they were dirtied and before the stop-the-world GC that is // examining cards here. assert(bottom < top, "ought to be at least one obj on a dirty card."); if (_boundary != NULL) { // We have a boundary outside of which we don't want to look // at objects, so create a filtering closure around the // oop closure before walking the region. FilteringClosure filter(_boundary, _cl); walk_mem_region_with_cl(mr, bottom, top, &filter); } else { // No boundary, simply walk the heap with the oop closure. walk_mem_region_with_cl(mr, bottom, top, _cl); } } // We must replicate this so that the static type of "FilteringClosure" // (see above) is apparent at the oop_iterate calls. #define ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \ void ContiguousSpaceDCTOC::walk_mem_region_with_cl(MemRegion mr, \ HeapWord* bottom, \ HeapWord* top, \ ClosureType* cl) { \ bottom += oop(bottom)->oop_iterate(cl, mr); \ if (bottom < top) { \ HeapWord* next_obj = bottom + oop(bottom)->size(); \ while (next_obj < top) { \ /* Bottom lies entirely below top, so we can call the */ \ /* non-memRegion version of oop_iterate below. */ \ oop(bottom)->oop_iterate(cl); \ bottom = next_obj; \ next_obj = bottom + oop(bottom)->size(); \ } \ /* Last object. */ \ oop(bottom)->oop_iterate(cl, mr); \ } \ } // (There are only two of these, rather than N, because the split is due // only to the introduction of the FilteringClosure, a local part of the // impl of this abstraction.) ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ExtendedOopClosure) ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure) DirtyCardToOopClosure* ContiguousSpace::new_dcto_cl(ExtendedOopClosure* cl, CardTableModRefBS::PrecisionStyle precision, HeapWord* boundary) { return new ContiguousSpaceDCTOC(this, cl, precision, boundary); } void Space::initialize(MemRegion mr, bool clear_space, bool mangle_space) { HeapWord* bottom = mr.start(); HeapWord* end = mr.end(); assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end), "invalid space boundaries"); set_bottom(bottom); set_end(end); if (clear_space) clear(mangle_space); } void Space::clear(bool mangle_space) { if (ZapUnusedHeapArea && mangle_space) { mangle_unused_area(); } } ContiguousSpace::ContiguousSpace(): CompactibleSpace(), _top(NULL), _concurrent_iteration_safe_limit(NULL) { _mangler = new GenSpaceMangler(this); } ContiguousSpace::~ContiguousSpace() { delete _mangler; } void ContiguousSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) { CompactibleSpace::initialize(mr, clear_space, mangle_space); set_concurrent_iteration_safe_limit(top()); } void ContiguousSpace::clear(bool mangle_space) { set_top(bottom()); set_saved_mark(); CompactibleSpace::clear(mangle_space); } bool ContiguousSpace::is_in(const void* p) const { return _bottom <= p && p < _top; } bool ContiguousSpace::is_free_block(const HeapWord* p) const { return p >= _top; } void OffsetTableContigSpace::clear(bool mangle_space) { ContiguousSpace::clear(mangle_space); _offsets.initialize_threshold(); } void OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) { Space::set_bottom(new_bottom); _offsets.set_bottom(new_bottom); } void OffsetTableContigSpace::set_end(HeapWord* new_end) { // Space should not advertize an increase in size // until after the underlying offest table has been enlarged. _offsets.resize(pointer_delta(new_end, bottom())); Space::set_end(new_end); } #ifndef PRODUCT void ContiguousSpace::set_top_for_allocations(HeapWord* v) { mangler()->set_top_for_allocations(v); } void ContiguousSpace::set_top_for_allocations() { mangler()->set_top_for_allocations(top()); } void ContiguousSpace::check_mangled_unused_area(HeapWord* limit) { mangler()->check_mangled_unused_area(limit); } void ContiguousSpace::check_mangled_unused_area_complete() { mangler()->check_mangled_unused_area_complete(); } // Mangled only the unused space that has not previously // been mangled and that has not been allocated since being // mangled. void ContiguousSpace::mangle_unused_area() { mangler()->mangle_unused_area(); } void ContiguousSpace::mangle_unused_area_complete() { mangler()->mangle_unused_area_complete(); } void ContiguousSpace::mangle_region(MemRegion mr) { // Although this method uses SpaceMangler::mangle_region() which // is not specific to a space, the when the ContiguousSpace version // is called, it is always with regard to a space and this // bounds checking is appropriate. MemRegion space_mr(bottom(), end()); assert(space_mr.contains(mr), "Mangling outside space"); SpaceMangler::mangle_region(mr); } #endif // NOT_PRODUCT void CompactibleSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) { Space::initialize(mr, clear_space, mangle_space); set_compaction_top(bottom()); _next_compaction_space = NULL; } void CompactibleSpace::clear(bool mangle_space) { Space::clear(mangle_space); _compaction_top = bottom(); } HeapWord* CompactibleSpace::forward(oop q, size_t size, CompactPoint* cp, HeapWord* compact_top) { // q is alive // First check if we should switch compaction space assert(this == cp->space, "'this' should be current compaction space."); size_t compaction_max_size = pointer_delta(end(), compact_top); while (size > compaction_max_size) { // switch to next compaction space cp->space->set_compaction_top(compact_top); cp->space = cp->space->next_compaction_space(); if (cp->space == NULL) { cp->gen = GenCollectedHeap::heap()->prev_gen(cp->gen); assert(cp->gen != NULL, "compaction must succeed"); cp->space = cp->gen->first_compaction_space(); assert(cp->space != NULL, "generation must have a first compaction space"); } compact_top = cp->space->bottom(); cp->space->set_compaction_top(compact_top); cp->threshold = cp->space->initialize_threshold(); compaction_max_size = pointer_delta(cp->space->end(), compact_top); } // store the forwarding pointer into the mark word if ((HeapWord*)q != compact_top) { q->forward_to(oop(compact_top)); assert(q->is_gc_marked(), "encoding the pointer should preserve the mark"); } else { // if the object isn't moving we can just set the mark to the default // mark and handle it specially later on. q->init_mark(); assert(q->forwardee() == NULL, "should be forwarded to NULL"); } compact_top += size; // we need to update the offset table so that the beginnings of objects can be // found during scavenge. Note that we are updating the offset table based on // where the object will be once the compaction phase finishes. if (compact_top > cp->threshold) cp->threshold = cp->space->cross_threshold(compact_top - size, compact_top); return compact_top; } bool CompactibleSpace::insert_deadspace(size_t& allowed_deadspace_words, HeapWord* q, size_t deadlength) { if (allowed_deadspace_words >= deadlength) { allowed_deadspace_words -= deadlength; CollectedHeap::fill_with_object(q, deadlength); oop(q)->set_mark(oop(q)->mark()->set_marked()); assert((int) deadlength == oop(q)->size(), "bad filler object size"); // Recall that we required "q == compaction_top". return true; } else { allowed_deadspace_words = 0; return false; } } #define block_is_always_obj(q) true #define obj_size(q) oop(q)->size() #define adjust_obj_size(s) s void CompactibleSpace::prepare_for_compaction(CompactPoint* cp) { SCAN_AND_FORWARD(cp, end, block_is_obj, block_size); } // Faster object search. void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) { SCAN_AND_FORWARD(cp, top, block_is_always_obj, obj_size); } void Space::adjust_pointers() { // adjust all the interior pointers to point at the new locations of objects // Used by MarkSweep::mark_sweep_phase3() // First check to see if there is any work to be done. if (used() == 0) { return; // Nothing to do. } // Otherwise... HeapWord* q = bottom(); HeapWord* t = end(); debug_only(HeapWord* prev_q = NULL); while (q < t) { if (oop(q)->is_gc_marked()) { // q is alive // point all the oops to the new location size_t size = oop(q)->adjust_pointers(); debug_only(prev_q = q); q += size; } else { // q is not a live object. But we're not in a compactible space, // So we don't have live ranges. debug_only(prev_q = q); q += block_size(q); assert(q > prev_q, "we should be moving forward through memory"); } } assert(q == t, "just checking"); } void CompactibleSpace::adjust_pointers() { // Check first is there is any work to do. if (used() == 0) { return; // Nothing to do. } SCAN_AND_ADJUST_POINTERS(adjust_obj_size); } void CompactibleSpace::compact() { SCAN_AND_COMPACT(obj_size); } void Space::print_short() const { print_short_on(tty); } void Space::print_short_on(outputStream* st) const { st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K, (int) ((double) used() * 100 / capacity())); } void Space::print() const { print_on(tty); } void Space::print_on(outputStream* st) const { print_short_on(st); st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")", bottom(), end()); } void ContiguousSpace::print_on(outputStream* st) const { print_short_on(st); st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", bottom(), top(), end()); } void OffsetTableContigSpace::print_on(outputStream* st) const { print_short_on(st); st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", bottom(), top(), _offsets.threshold(), end()); } void ContiguousSpace::verify() const { HeapWord* p = bottom(); HeapWord* t = top(); HeapWord* prev_p = NULL; while (p < t) { oop(p)->verify(); prev_p = p; p += oop(p)->size(); } guarantee(p == top(), "end of last object must match end of space"); if (top() != end()) { guarantee(top() == block_start_const(end()-1) && top() == block_start_const(top()), "top should be start of unallocated block, if it exists"); } } void Space::oop_iterate(ExtendedOopClosure* blk) { ObjectToOopClosure blk2(blk); object_iterate(&blk2); } HeapWord* Space::object_iterate_careful(ObjectClosureCareful* cl) { guarantee(false, "NYI"); return bottom(); } HeapWord* Space::object_iterate_careful_m(MemRegion mr, ObjectClosureCareful* cl) { guarantee(false, "NYI"); return bottom(); } void Space::object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl) { assert(!mr.is_empty(), "Should be non-empty"); // We use MemRegion(bottom(), end()) rather than used_region() below // because the two are not necessarily equal for some kinds of // spaces, in particular, certain kinds of free list spaces. // We could use the more complicated but more precise: // MemRegion(used_region().start(), round_to(used_region().end(), CardSize)) // but the slight imprecision seems acceptable in the assertion check. assert(MemRegion(bottom(), end()).contains(mr), "Should be within used space"); HeapWord* prev = cl->previous(); // max address from last time if (prev >= mr.end()) { // nothing to do return; } // This assert will not work when we go from cms space to perm // space, and use same closure. Easy fix deferred for later. XXX YSR // assert(prev == NULL || contains(prev), "Should be within space"); bool last_was_obj_array = false; HeapWord *blk_start_addr, *region_start_addr; if (prev > mr.start()) { region_start_addr = prev; blk_start_addr = prev; // The previous invocation may have pushed "prev" beyond the // last allocated block yet there may be still be blocks // in this region due to a particular coalescing policy. // Relax the assertion so that the case where the unallocated // block is maintained and "prev" is beyond the unallocated // block does not cause the assertion to fire. assert((BlockOffsetArrayUseUnallocatedBlock && (!is_in(prev))) || (blk_start_addr == block_start(region_start_addr)), "invariant"); } else { region_start_addr = mr.start(); blk_start_addr = block_start(region_start_addr); } HeapWord* region_end_addr = mr.end(); MemRegion derived_mr(region_start_addr, region_end_addr); while (blk_start_addr < region_end_addr) { const size_t size = block_size(blk_start_addr); if (block_is_obj(blk_start_addr)) { last_was_obj_array = cl->do_object_bm(oop(blk_start_addr), derived_mr); } else { last_was_obj_array = false; } blk_start_addr += size; } if (!last_was_obj_array) { assert((bottom() <= blk_start_addr) && (blk_start_addr <= end()), "Should be within (closed) used space"); assert(blk_start_addr > prev, "Invariant"); cl->set_previous(blk_start_addr); // min address for next time } } bool Space::obj_is_alive(const HeapWord* p) const { assert (block_is_obj(p), "The address should point to an object"); return true; } void ContiguousSpace::object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl) { assert(!mr.is_empty(), "Should be non-empty"); assert(used_region().contains(mr), "Should be within used space"); HeapWord* prev = cl->previous(); // max address from last time if (prev >= mr.end()) { // nothing to do return; } // See comment above (in more general method above) in case you // happen to use this method. assert(prev == NULL || is_in_reserved(prev), "Should be within space"); bool last_was_obj_array = false; HeapWord *obj_start_addr, *region_start_addr; if (prev > mr.start()) { region_start_addr = prev; obj_start_addr = prev; assert(obj_start_addr == block_start(region_start_addr), "invariant"); } else { region_start_addr = mr.start(); obj_start_addr = block_start(region_start_addr); } HeapWord* region_end_addr = mr.end(); MemRegion derived_mr(region_start_addr, region_end_addr); while (obj_start_addr < region_end_addr) { oop obj = oop(obj_start_addr); const size_t size = obj->size(); last_was_obj_array = cl->do_object_bm(obj, derived_mr); obj_start_addr += size; } if (!last_was_obj_array) { assert((bottom() <= obj_start_addr) && (obj_start_addr <= end()), "Should be within (closed) used space"); assert(obj_start_addr > prev, "Invariant"); cl->set_previous(obj_start_addr); // min address for next time } } #if INCLUDE_ALL_GCS #define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \ \ void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\ HeapWord* obj_addr = mr.start(); \ HeapWord* t = mr.end(); \ while (obj_addr < t) { \ assert(oop(obj_addr)->is_oop(), "Should be an oop"); \ obj_addr += oop(obj_addr)->oop_iterate(blk); \ } \ } ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN) #undef ContigSpace_PAR_OOP_ITERATE_DEFN #endif // INCLUDE_ALL_GCS void ContiguousSpace::oop_iterate(ExtendedOopClosure* blk) { if (is_empty()) return; HeapWord* obj_addr = bottom(); HeapWord* t = top(); // Could call objects iterate, but this is easier. while (obj_addr < t) { obj_addr += oop(obj_addr)->oop_iterate(blk); } } void ContiguousSpace::oop_iterate(MemRegion mr, ExtendedOopClosure* blk) { if (is_empty()) { return; } MemRegion cur = MemRegion(bottom(), top()); mr = mr.intersection(cur); if (mr.is_empty()) { return; } if (mr.equals(cur)) { oop_iterate(blk); return; } assert(mr.end() <= top(), "just took an intersection above"); HeapWord* obj_addr = block_start(mr.start()); HeapWord* t = mr.end(); // Handle first object specially. oop obj = oop(obj_addr); SpaceMemRegionOopsIterClosure smr_blk(blk, mr); obj_addr += obj->oop_iterate(&smr_blk); while (obj_addr < t) { oop obj = oop(obj_addr); assert(obj->is_oop(), "expected an oop"); obj_addr += obj->size(); // If "obj_addr" is not greater than top, then the // entire object "obj" is within the region. if (obj_addr <= t) { obj->oop_iterate(blk); } else { // "obj" extends beyond end of region obj->oop_iterate(&smr_blk); break; } }; } void ContiguousSpace::object_iterate(ObjectClosure* blk) { if (is_empty()) return; WaterMark bm = bottom_mark(); object_iterate_from(bm, blk); } // For a continguous space object_iterate() and safe_object_iterate() // are the same. void ContiguousSpace::safe_object_iterate(ObjectClosure* blk) { object_iterate(blk); } void ContiguousSpace::object_iterate_from(WaterMark mark, ObjectClosure* blk) { assert(mark.space() == this, "Mark does not match space"); HeapWord* p = mark.point(); while (p < top()) { blk->do_object(oop(p)); p += oop(p)->size(); } } HeapWord* ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) { HeapWord * limit = concurrent_iteration_safe_limit(); assert(limit <= top(), "sanity check"); for (HeapWord* p = bottom(); p < limit;) { size_t size = blk->do_object_careful(oop(p)); if (size == 0) { return p; // failed at p } else { p += size; } } return NULL; // all done } #define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ \ void ContiguousSpace:: \ oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \ HeapWord* t; \ HeapWord* p = saved_mark_word(); \ assert(p != NULL, "expected saved mark"); \ \ const intx interval = PrefetchScanIntervalInBytes; \ do { \ t = top(); \ while (p < t) { \ Prefetch::write(p, interval); \ debug_only(HeapWord* prev = p); \ oop m = oop(p); \ p += m->oop_iterate(blk); \ } \ } while (t < top()); \ \ set_saved_mark_word(p); \ } ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN) #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN // Very general, slow implementation. HeapWord* ContiguousSpace::block_start_const(const void* p) const { assert(MemRegion(bottom(), end()).contains(p), err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")", p, bottom(), end())); if (p >= top()) { return top(); } else { HeapWord* last = bottom(); HeapWord* cur = last; while (cur <= p) { last = cur; cur += oop(cur)->size(); } assert(oop(last)->is_oop(), err_msg(PTR_FORMAT " should be an object start", last)); return last; } } size_t ContiguousSpace::block_size(const HeapWord* p) const { assert(MemRegion(bottom(), end()).contains(p), err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")", p, bottom(), end())); HeapWord* current_top = top(); assert(p <= current_top, err_msg("p > current top - p: " PTR_FORMAT ", current top: " PTR_FORMAT, p, current_top)); assert(p == current_top || oop(p)->is_oop(), err_msg("p (" PTR_FORMAT ") is not a block start - " "current_top: " PTR_FORMAT ", is_oop: %s", p, current_top, BOOL_TO_STR(oop(p)->is_oop()))); if (p < current_top) { return oop(p)->size(); } else { assert(p == current_top, "just checking"); return pointer_delta(end(), (HeapWord*) p); } } // This version requires locking. inline HeapWord* ContiguousSpace::allocate_impl(size_t size, HeapWord* const end_value) { // In G1 there are places where a GC worker can allocates into a // region using this serial allocation code without being prone to a // race with other GC workers (we ensure that no other GC worker can // access the same region at the same time). So the assert below is // too strong in the case of G1. assert(Heap_lock->owned_by_self() || (SafepointSynchronize::is_at_safepoint() && (Thread::current()->is_VM_thread() || UseG1GC)), "not locked"); HeapWord* obj = top(); if (pointer_delta(end_value, obj) >= size) { HeapWord* new_top = obj + size; set_top(new_top); assert(is_aligned(obj) && is_aligned(new_top), "checking alignment"); return obj; } else { return NULL; } } // This version is lock-free. inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size, HeapWord* const end_value) { do { HeapWord* obj = top(); if (pointer_delta(end_value, obj) >= size) { HeapWord* new_top = obj + size; HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj); // result can be one of two: // the old top value: the exchange succeeded // otherwise: the new value of the top is returned. if (result == obj) { assert(is_aligned(obj) && is_aligned(new_top), "checking alignment"); return obj; } } else { return NULL; } } while (true); } // Requires locking. HeapWord* ContiguousSpace::allocate(size_t size) { return allocate_impl(size, end()); } // Lock-free. HeapWord* ContiguousSpace::par_allocate(size_t size) { return par_allocate_impl(size, end()); } void ContiguousSpace::allocate_temporary_filler(int factor) { // allocate temporary type array decreasing free size with factor 'factor' assert(factor >= 0, "just checking"); size_t size = pointer_delta(end(), top()); // if space is full, return if (size == 0) return; if (factor > 0) { size -= size/factor; } size = align_object_size(size); const size_t array_header_size = typeArrayOopDesc::header_size(T_INT); if (size >= (size_t)align_object_size(array_header_size)) { size_t length = (size - array_header_size) * (HeapWordSize / sizeof(jint)); // allocate uninitialized int array typeArrayOop t = (typeArrayOop) allocate(size); assert(t != NULL, "allocation should succeed"); t->set_mark(markOopDesc::prototype()); t->set_klass(Universe::intArrayKlassObj()); t->set_length((int)length); } else { assert(size == CollectedHeap::min_fill_size(), "size for smallest fake object doesn't match"); instanceOop obj = (instanceOop) allocate(size); obj->set_mark(markOopDesc::prototype()); obj->set_klass_gap(0); obj->set_klass(SystemDictionary::Object_klass()); } } void EdenSpace::clear(bool mangle_space) { ContiguousSpace::clear(mangle_space); set_soft_end(end()); } // Requires locking. HeapWord* EdenSpace::allocate(size_t size) { return allocate_impl(size, soft_end()); } // Lock-free. HeapWord* EdenSpace::par_allocate(size_t size) { return par_allocate_impl(size, soft_end()); } HeapWord* ConcEdenSpace::par_allocate(size_t size) { do { // The invariant is top() should be read before end() because // top() can't be greater than end(), so if an update of _soft_end // occurs between 'end_val = end();' and 'top_val = top();' top() // also can grow up to the new end() and the condition // 'top_val > end_val' is true. To ensure the loading order // OrderAccess::loadload() is required after top() read. HeapWord* obj = top(); OrderAccess::loadload(); if (pointer_delta(*soft_end_addr(), obj) >= size) { HeapWord* new_top = obj + size; HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj); // result can be one of two: // the old top value: the exchange succeeded // otherwise: the new value of the top is returned. if (result == obj) { assert(is_aligned(obj) && is_aligned(new_top), "checking alignment"); return obj; } } else { return NULL; } } while (true); } HeapWord* OffsetTableContigSpace::initialize_threshold() { return _offsets.initialize_threshold(); } HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) { _offsets.alloc_block(start, end); return _offsets.threshold(); } OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray, MemRegion mr) : _offsets(sharedOffsetArray, mr), _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true) { _offsets.set_contig_space(this); initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle); } #define OBJ_SAMPLE_INTERVAL 0 #define BLOCK_SAMPLE_INTERVAL 100 void OffsetTableContigSpace::verify() const { HeapWord* p = bottom(); HeapWord* prev_p = NULL; int objs = 0; int blocks = 0; if (VerifyObjectStartArray) { _offsets.verify(); } while (p < top()) { size_t size = oop(p)->size(); // For a sampling of objects in the space, find it using the // block offset table. if (blocks == BLOCK_SAMPLE_INTERVAL) { guarantee(p == block_start_const(p + (size/2)), "check offset computation"); blocks = 0; } else { blocks++; } if (objs == OBJ_SAMPLE_INTERVAL) { oop(p)->verify(); objs = 0; } else { objs++; } prev_p = p; p += size; } guarantee(p == top(), "end of last object must match end of space"); } size_t TenuredSpace::allowed_dead_ratio() const { return MarkSweepDeadRatio; } Other Java examples (source code examples)Here is a short list of links related to this Java space.cpp source code file: |
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